1. Field of the Invention
The present invention relates to a method of manufacturing a piezoelectric actuator and a method of manufacturing a liquid transporting apparatus.
2. Description of the Related Art
Conventionally, as an ink-jet head which jets ink from nozzles, there is know one having a piezoelectric actuator which applies a jetting pressure to ink using a piezoelectric deformation (piezoelectric distortion) generated when an electric field operates on a piezoelectric material layer.
For example, a piezoelectric actuator of an ink-jet head described in Japanese Patent Application Laid-open No. 2006-96034 has a vibration plate which is made of metal and covers a plurality of pressure chambers formed in a channel unit, a piezoelectric layer arranged on an upper surface of the vibration plate, and a plurality of individual electrodes arranged respectively in areas facing the plurality of pressure chambers on an upper surface of the piezoelectric layer. Then, in this piezoelectric actuator, when a predetermined drive voltage is applied between the individual electrodes on the upper surface of the piezoelectric layer and the vibration plate as a common electrode located on a lower side of the piezoelectric layer, the piezoelectric layer contracts and a bending deformation is generated in the vibration plate. Then, the volume in the pressure chambers changes according to this deformation of the vibration plate, and thereby a jetting pressure is applied to the ink in the pressure chambers.
Further, in the piezoelectric actuator of Japanese Patent Application Laid-open No. 2006-96034, recess portions (trenches, grooves) are formed in an upper surface of a vibration plate. As the recess portions, there are disclosed one formed in an area facing a pressure chamber and one formed in an outside area not facing a pressure chamber. Then the piezoelectric layer is formed by depositing particles of a piezoelectric material on the entire upper surface of the vibration plate including the recess portions using an aerosol deposition method (AD method) or the like. Then, since it is more difficult for particles to be deposited in a recess portion than in a surrounding flat area thereof, the piezoelectric layer becomes partly thinner in areas of the vibration plate where the recess portions are formed. As a result, in the areas where the recess portions are formed, the thickness of both the vibration plate and the piezoelectric layer, namely, the rigidity of the piezoelectric actuator becomes low locally.
When the recess portions of the vibration plate are arranged in the areas facing the pressure chambers, the vibration plate can be easily deformed in the areas facing the pressure chambers. In other words, it becomes possible to reduce the drive voltage needed for obtaining a predetermined deformation amount (namely, a volume change amount in a pressure chamber). Further, when the recess portions of the vibration plate are each arranged in an area between adjacent pressure chambers, pressure fluctuation (crosstalk) due to propagation of the deformation of the vibration plate between the adjacent pressure chambers from one to the other is suppressed.
In view of reducing the drive voltage by facilitating the deformation of the vibration plate in the areas facing the pressure chambers, or suppression of the crosstalk between adjacent pressure chambers, it is preferable that no piezoelectric material is deposited on surfaces of the recess portions, so that the rigidity of the piezoelectric actuator in the areas where the recess portions are formed is decreased further. However, in the piezoelectric actuator described in Japanese Patent Application Laid-open No. 2006-96034, the amount of the piezoelectric material deposited in the recess portions is smaller than on a flat area other than the recess portions, but the piezoelectric material still deposits therein to some degree. Further, although it is possible to remove the piezoelectric layer deposited in the recess portions by laser or the like, the removal requires high processing accuracy so as not to remove the piezoelectric layer on the necessary areas, and addition of such steps increases the manufacturing cost.